Re: Q: on redefinition of equal

[eachus@spectre.mitre.org (Robert I. Eachus)]

In article <4k131kINN2ac@thalamus.cis.ohio-state.edu> dgibson@thalamus.cis.ohio-state.edu (david scott gibson) writes:

  > In article <9604031559.AA05644@most>,
  > W. Wesley Groleau (Wes) <wwgrol@PSESERV3.FW.HAC.COM> wrote:

  > >How much will it cost over the life cycle to have maintenance programmers
  > >replacing
  > >   if (A = B) = True then
  > >with
  > >   if A = B then
  > >only to (attempt to) compile and then change it back?

  > Well, of course, this is only one of the problems with such a
  > strategy.  BTW, I consider

  >     if Is_True(A = B) then 

  > preferable to using two different ='s since appears a little less
  > confusing.  Note that I'm only exploring possibilities at this point!

  > >Of course, with GNAT you can change the compiler to accept the standard
  > >form with your new type Bool  :-)

  First, a big suprise for all you Ada users:

  RM95 5.3(4): "A condition is expected to be of any boolean type."

  The rule in Ada 83 is the same.  If Bool is derived directly or
indirectly from Standard.Boolean, then it is a boolean type.  This is
very useful if you want to provide an enumeration representation
clause to match hardware.

   However if you need a three valued type, may I suggest that
if...then...else be replaced with:

   case X is
     when True   => ....
     when False  => ....
     when others =>
   end case;








--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...